As music has escaped the constraints of physical media, the rap mixtape has shed much of its reputation as a second-class format—rap musicians, critics, and fans have begun to treat it as a legitimate alternative to the proper album (whatever "proper album" even means anymore). And there have been few mixtapes that wear ambition on their sleeves like Fat Trel's recent Nightmare on E Street. The beats come from a who's who of current mixtape-production phenoms (Lex Luger, Big K.R.I.T., Harry Fraud, Boss Major), but more important they represent an impressively broad range of styles—and Trel adapts his heavily syncopated flow to every one, showing off his gymnast-level flexibility. Granted, Nightmare's rap-dubstep hybrid continues in the burgeoning American tradition of terrible rap-dubstep hybrids, but you can't knock him for being willing to give it a shot. —Miles RaymerJuicy J headlines; Smoke DZA, Fat Trel, Joey Bada$$ with Pro Era, Cashius Green with Pheo, Short Stop, and Corner Boy P open.